21816817759 has 12 divisors (see below), whose sum is σ = 24227703472. Its totient is φ = 19628991360.

The previous prime is 21816817747. The next prime is 21816817783. The reversal of 21816817759 is 95771861812.

It is not a de Polignac number, because 21816817759 - 2⁵ = 21816817727 is a prime.

It is a hoax number, since the sum of its digits (55) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21816817259) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 917667 + ... + 941140.

Almost surely, 2^21816817759 is an apocalyptic number.

21816817759 is a deficient number, since it is larger than the sum of its proper divisors (2410885713).

21816817759 is a wasteful number, since it uses less digits than its factorization.

21816817759 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1858926 (or 1858915 counting only the distinct ones).

The product of its digits is 1693440, while the sum is 55.

The spelling of 21816817759 in words is "twenty-one billion, eight hundred sixteen million, eight hundred seventeen thousand, seven hundred fifty-nine".